UPSTREAM: <carry>: Rate-limit concurrent DRBG inits at request entry …

[sdodson]

In FIPS/CGo mode, the first crypto/rand call on a new OS thread triggers
per-thread DRBG initialization via OpenSSL. Go creates a new OS thread for
each concurrent CGo call, so a kubelet watch reconnect storm after apiserver
restart can simultaneously trigger thousands of DRBG inits, exhausting the
10k OS thread limit.

Add a 64-slot semaphore at APIServerHandler.ServeHTTP that gates each request's
initial crypto/rand read. This caps concurrent DRBG inits to 64, staggering
thread creation over time rather than allowing an instantaneous burst.

Note: a nil or zero-length read does not trigger DRBG init in OpenSSL; at
least one byte must be read to force initialization.

This approach covers all crypto/rand callers in the request path rather than
individual call sites, and is complementary to the WithAuditInit fix (042a4ae).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository: openshift/coderabbit/.coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: a1814f4e-b2b9-425e-b489-585f595af93a

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands.}

[openshift-ci-robot]

@sdodson: the contents of this pull request could not be automatically validated.

The following commits could not be validated and must be approved by a top-level approver:

• 823e59b|UPSTREAM: : Rate-limit concurrent DRBG inits at request entry point: does not specify an upstream backport in the commit message

Comment /validate-backports to re-evaluate validity of the upstream PRs, for example when they are merged upstream.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: sdodson
Once this PR has been reviewed and has the lgtm label, please assign p0lyn0mial for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• DOWNSTREAM_OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment